Abstract:
Water is a limiting factor in the distribution and growth of trees. Changing climatic
conditions are likely to significantly effect tree species development. The planting and
establishment of trees needs to take into account these changing factors in terms of
design and species selection. This study looked at survival and growth of newly planted
trees under field scale conditions and the effects of soil water availability and ground
treatments. The experiment followed a blocked plan allowing a line source design to
irrigate three tree species, ash, Douglas fir and oak. Each plot of 90 trees was divided
into 5 irrigation subplots with varying levels of water application. Two ground
treatments, bare ground and vegetated were also applied. Over a three year period,
there was a significant effect of species (P<0.001) and herbicide application (P<0.01)
on tree survival. Tree height and diameter were significant (P<0.01) between species
and herbicide. Irrigation had a significant effect on growth rates of all species with no
effect on survival. Ground vegetation biomass significantly increased in high irrigation
subplots (P<0.01), with increasing festuca rubra dominance decreasing plant diversity
(R2=0.8533). The results suggest that soil moisture availability increases tree growth
but does not significantly improve survival rates of the tree species studied. Water is a
key factor in the establishment of trees with maintained soil moisture increasing growth
development of individuals. Therefore site and species selection are essential in the
design of woodland plantings for conservation, recreation and commercial activities.
